EDA500 connecting directly to PC

Does your PC eSATA controller support port multiplication?  If it doesn't say it does, it probably doesn't.  Most motherboard eSATA connections don't.  That could be why it's not working for you on the PC.  Or, it just may not be possible.  The OP posted that he is getting a controller that does support it, so you may want to wait and see if he has better luck.  But even if it does work, you might not be able to use your drives with the data on them.  I can't see the part number on the big IC well enough in the pictures, but it looks to be something more than just a SATA multiplier, quite likely programmable.

You definately don't want to use those drives in a NAS (internally or in an expansion chassis), as the contents will be wiped.  I think you should be looking for a USB3 or SATA drive dock.  Note that a DAS that uses RAID (such as a Drobo 5c or 5d) is also not what you want, as they also need to reformat the drives to create the RAID.  Make sure it states it suports drives of at least 4TB.  I'd expect anything with USB3 to do so, but never assume.  I'm not aware of any Netgear product that's designed for what you want.